As a user, all beit more in the Sandbox than in Revit these days, I agree with @Aaron_Maller he pretty much hit the nail on the head. I have a little different outlook on option #3, but other than that hit that nail right on the nail right on the head 
I also use the archi-lab package, and the way I deal with that is to just create a “2021” or whatever year I’m using folder and put the packaging in there. Then I only add that folder path in that version of Revit (so Revit 2021 only sees the “2021” folder, and Revit 2022 only sees the “2022” folder.
For option 3, only supporting current version, as long as you don’t remove the past versions I don’t see a big issue with this. Yes some people will hit download and get the “wrong” version if they are still on Revit 2021. But in reality if they are still on Revit 2021, they likely don’t want the latest and greatest anyway because they are on an old version of Revit and an old version of Dynamo. They have a graph that works and the less changes the better. Running the latest version is great for testing and new features, but not great for product, that ship doesn’t turn on a dime as we all know.
In the end @john_pierson I vote for what’s the least work for you! You have done so much for this community and given so much of your time and yourself it is just not fair to ask for any more from you! 
This is why it’s so great that you’ve made this package open source so others can learn from it and take up the charge to improve it and move it forward.